
Underfloor Heating Non-Mixing Direct Circulation Pump Set
The Underfloor Heating Non-Mixing Pump Set is a professional heating circulation component designed to support circulation and control within a compatible water-based heating system. It is presented with the stated size, output, connection or configuration so installers and buyers can identify the required option accurately.

Underfloor Heating Non-Mixing Direct Circulation Pump Set
The Underfloor Heating Non-Mixing Pump Set is a professional heating circulation component designed to support circulation and control within a compatible water-based heating system. It is presented with the stated size, output, connection or configuration so installers and buyers can identify the required option accurately.
Quick Trade Summary: Underfloor Heating Non-Mixing Direct Circulation Pump Set
The Underfloor Heating Non-Mixing Pump Set (ZL-2536C) is specifically designed for modern low-temperature heating systems where primary water is already weather-compensated to the correct floor design temperature (30°C–42°C)—such as Monobloc Air Source Heat Pumps, Ground Source Heat Pumps, and Heat Interface Units (HIUs). By omitting a mechanical thermostatic mixing valve, it eliminates parasitic pressure drop and maximizes heat pump COP efficiency.
Trade Engineering Standards & Hydraulic Application
In hydronic underfloor heating installations, matching the circulation pump's head and volumetric flow rate to circuit pressure drop is essential to prevent cold spots, actuator noise, and premature component wear. The Underfloor Heating Non-Mixing Direct Circulation Pump Set is precision-engineered to British Standard BS EN 1264 and CIBSE hydronic sizing standards, guaranteeing balanced loop flow across modern UK domestic and commercial heating systems.
Engineering Specifications & Technical Standards
| Parameter | Specification Standard |
|---|---|
| Model / SKU | ZL-2536C Direct Non-Mixing Unit |
| Application | Dedicated Low-Temperature Heat Pump & HIU Underfloor Heating |
| Manifold Connections | 1" BSP Male Swivel Union Connections (210mm Centres) |
| Primary Feed Connections | 3/4" BSP Female / 1" Male |
| Circulation Pump | A-Rated High Efficiency 6m Circulator Included |
| Flow Resistance (Kv) | Ultra-Low Hydraulic Drag (Unrestricted Direct Flow) |
| Isolation & Draining | Integrated Quarter-Turn Red/Blue Lever Ball Valves with Temperature Wells |
| Maximum Working Pressure | 10 Bar (PN10) |
| Maximum Fluid Temperature | 95°C |
| Standards & Directives | BS EN 1264, MCS MIS 3005 Heat Pump Compliant, CE, UKCA |
Step-by-Step Installation & Commissioning Protocol
- Hydraulic Isolation & Depressurisation: Close manifold isolation ball valves and isolate primary boiler feeds before loosening union nuts. Have a trade catchment tray ready for residual water.
- Gasket Seating & Mechanical Fit: Inspect flat union mating faces. Insert fresh 1½" EPDM sealing washers. Position pump body strictly with the motor shaft horizontal (never pointing vertically up or down) to ensure water-lubricated bearing longevity.
- Torque Alignment: Tighten 1½" BSP union nuts by hand, then secure with adjustable pump spanners to recommended torque (approximately 45–55 Nm). Do not overtighten or pinch the rubber gasket.
- Electrical Termination: Wire live, neutral, and earth into the manifold wiring centre or 230V room thermostat switched live output. Verify earth continuity in accordance with BS 7671 (IET Wiring Regulations 18th Edition).
- Venting & Air Purging: Fill the manifold circuits loop by loop until flowmeter sight glasses run crystal clear of trapped microbubbles. Power on pump and allow automatic air-venting routine to complete before locking final operational mode.
- Flow Balancing: Calibrate flowmeters on each manifold port according to CIBSE design calculation sheets (typically 1.5 to 2.5 Litres/min per loop depending on loop length).
Frequently Asked Questions: Underfloor Heating Non-Mixing Direct Circulation Pump Set
When should an installer choose a non-mixing pump set over a thermostatic mixing set?
Choose non-mixing whenever the heat source (such as an air source heat pump) directly weather-compensates water temperature to 32°C–40°C. Adding a thermostatic mixing valve on low-temperature heat pumps causes unnecessary flow restriction and lowers COP.
Why is an additional pump needed if the heat pump has an internal circulator?
Heat pump internal circulators often lack the dynamic head to overcome index loop friction on multi-port manifolds when separated by a low-loss header or buffer tank. This secondary pump provides dedicated manifold loop circulation.
Does this set include temperature gauges?
Yes, both flow and return manifold connection elbows feature built-in dial thermometers to verify real-time ΔT temperature differential.
What manifold port centres are required?
Standard 210mm vertical spacing between upper and lower manifold bars, matching all UK stainless steel and brass manifolds.
Are isolation valves built into the set?
Yes, heavy-duty full-bore isolation ball valves are included, allowing the pump to be serviced or replaced without draining the entire underfloor heating pipe array.
Is this pump unit MCS compliant?
Yes, fully compliant with MCS MIS 3005 domestic heat pump installation standards for secondary hydronic distribution.
Order the Underfloor Heating Non-Mixing Direct Circulation Pump Set with Trade Delivery
Genuine heating and hydronic supplies in stock for immediate dispatch. Backed by full UK manufacturer warranty and dedicated technical support.
Quick Trade Summary: Underfloor Heating Non-Mixing Direct Circulation Pump Set
The Underfloor Heating Non-Mixing Pump Set (ZL-2536C) is specifically designed for modern low-temperature heating systems where primary water is already weather-compensated to the correct floor design temperature (30°C–42°C)—such as Monobloc Air Source Heat Pumps, Ground Source Heat Pumps, and Heat Interface Units (HIUs). By omitting a mechanical thermostatic mixing valve, it eliminates parasitic pressure drop and maximizes heat pump COP efficiency.
Trade Engineering Standards & Hydraulic Application
In hydronic underfloor heating installations, matching the circulation pump's head and volumetric flow rate to circuit pressure drop is essential to prevent cold spots, actuator noise, and premature component wear. The Underfloor Heating Non-Mixing Direct Circulation Pump Set is precision-engineered to British Standard BS EN 1264 and CIBSE hydronic sizing standards, guaranteeing balanced loop flow across modern UK domestic and commercial heating systems.
Engineering Specifications & Technical Standards
| Parameter | Specification Standard |
|---|---|
| Model / SKU | ZL-2536C Direct Non-Mixing Unit |
| Application | Dedicated Low-Temperature Heat Pump & HIU Underfloor Heating |
| Manifold Connections | 1" BSP Male Swivel Union Connections (210mm Centres) |
| Primary Feed Connections | 3/4" BSP Female / 1" Male |
| Circulation Pump | A-Rated High Efficiency 6m Circulator Included |
| Flow Resistance (Kv) | Ultra-Low Hydraulic Drag (Unrestricted Direct Flow) |
| Isolation & Draining | Integrated Quarter-Turn Red/Blue Lever Ball Valves with Temperature Wells |
| Maximum Working Pressure | 10 Bar (PN10) |
| Maximum Fluid Temperature | 95°C |
| Standards & Directives | BS EN 1264, MCS MIS 3005 Heat Pump Compliant, CE, UKCA |
Step-by-Step Installation & Commissioning Protocol
- Hydraulic Isolation & Depressurisation: Close manifold isolation ball valves and isolate primary boiler feeds before loosening union nuts. Have a trade catchment tray ready for residual water.
- Gasket Seating & Mechanical Fit: Inspect flat union mating faces. Insert fresh 1½" EPDM sealing washers. Position pump body strictly with the motor shaft horizontal (never pointing vertically up or down) to ensure water-lubricated bearing longevity.
- Torque Alignment: Tighten 1½" BSP union nuts by hand, then secure with adjustable pump spanners to recommended torque (approximately 45–55 Nm). Do not overtighten or pinch the rubber gasket.
- Electrical Termination: Wire live, neutral, and earth into the manifold wiring centre or 230V room thermostat switched live output. Verify earth continuity in accordance with BS 7671 (IET Wiring Regulations 18th Edition).
- Venting & Air Purging: Fill the manifold circuits loop by loop until flowmeter sight glasses run crystal clear of trapped microbubbles. Power on pump and allow automatic air-venting routine to complete before locking final operational mode.
- Flow Balancing: Calibrate flowmeters on each manifold port according to CIBSE design calculation sheets (typically 1.5 to 2.5 Litres/min per loop depending on loop length).
Frequently Asked Questions: Underfloor Heating Non-Mixing Direct Circulation Pump Set
When should an installer choose a non-mixing pump set over a thermostatic mixing set?
Choose non-mixing whenever the heat source (such as an air source heat pump) directly weather-compensates water temperature to 32°C–40°C. Adding a thermostatic mixing valve on low-temperature heat pumps causes unnecessary flow restriction and lowers COP.
Why is an additional pump needed if the heat pump has an internal circulator?
Heat pump internal circulators often lack the dynamic head to overcome index loop friction on multi-port manifolds when separated by a low-loss header or buffer tank. This secondary pump provides dedicated manifold loop circulation.
Does this set include temperature gauges?
Yes, both flow and return manifold connection elbows feature built-in dial thermometers to verify real-time ΔT temperature differential.
What manifold port centres are required?
Standard 210mm vertical spacing between upper and lower manifold bars, matching all UK stainless steel and brass manifolds.
Are isolation valves built into the set?
Yes, heavy-duty full-bore isolation ball valves are included, allowing the pump to be serviced or replaced without draining the entire underfloor heating pipe array.
Is this pump unit MCS compliant?
Yes, fully compliant with MCS MIS 3005 domestic heat pump installation standards for secondary hydronic distribution.
Order the Underfloor Heating Non-Mixing Direct Circulation Pump Set with Trade Delivery
Genuine heating and hydronic supplies in stock for immediate dispatch. Backed by full UK manufacturer warranty and dedicated technical support.













